Micro imaging system, imaging apparatus and electronic device

ABSTRACT

A micro imaging system includes, in order from an object side to an image side: a first lens element having negative refractive power; a second lens element having positive refractive power; and a third lens element with negative refractive power having an object-side surface being concave in a paraxial region thereof. There are a total of three lens elements in the micro imaging system.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/254,840 filed on Jan. 23, 2019, now approved, which is a continuationof U.S. application Ser. No. 15/455,499 filed on Mar. 10, 2017, nowpatented and claims priority to Taiwan Application Serial Number105134014, filed on Oct. 21, 2016, which is incorporated by referenceherein in its entirety.

BACKGROUND Technical Field

The present disclosure relates to a micro imaging system and an imagingapparatus, and more particularly, to a micro imaging system and animaging apparatus applicable to electronic devices.

Description of Related Art

As camera modules being widely utilized, using cameras to fulfillvarious needs has become a trend of technological developments. Inaddition, with rapid developments in medical technology, cameras havebecome essential components to aid physicians in diagnoses andtreatments, especially for applications in the precision instruments orin living organism with only limited space which require higherenvironmental tolerance. Meanwhile, in order to meet variousrequirements for applications such as intelligent electronics, medicaldevices, precision instruments, car devices, recognition devices,entertainment devices, sports devices and intelligent home systems, lensassemblies with various features are hence being developed.

Conventional lens assemblies with a wide view angle are usually equippedwith spherical glass lenses and this arrangement is difficult inreducing the size of the lens assemblies and achieving the goal ofminiaturization. The view angles of the miniaturized imaging systemsthat are currently available with high image quality are insufficient tocapture wider range images. Therefore, the conventional optical lens hasfailed to adapt to the current trend in the technological development.

SUMMARY

According to one aspect of the present disclosure, a micro imagingsystem comprising, in order from an object side to an image side: afirst lens element having negative refractive power; a second lenselement having positive refractive power; and a third lens element withnegative refractive power having an object-side surface being concave ina paraxial region thereof, wherein the micro imaging system has a totalof three lens elements; a central thickness of the first lens element isCT1, a central thickness of the second lens element is CT2, an axialdistance between the first lens element and the second lens element isT12, a focal length of the micro imaging system is f, a curvature radiusof the object-side surface of the third lens element is R5, a curvatureradius of an image-side surface of the third lens element is R6, and thefollowing conditions are satisfied:0.10CT2/CT1<1.80;0.45<T12/f<5.0;|R5/R6|<0.70.

According to another aspect of the present disclosure, a micro imagingsystem comprises, in order from an object side to an image side: a firstlens element; a second lens element having positive refractive power;and a third lens element with negative refractive power having anobject-side surface being concave in a paraxial region thereof, whereinthe micro imaging system has a total of three lens elements; a centralthickness of the first lens element is CT1, a central thickness of thesecond lens element is CT2, a focal length of the first lens element isf1, a focal length of the second lens element is f2, a sum of axialdistances between every two adjacent lens elements of the micro imagingsystem is ΣAT, a sum of central thicknesses of the first lens element,the second lens element, and the third lens element is ΣCT, and thefollowing conditions are satisfied:0.10<CT2/CT1<1.10;−1.30<f2/f1<0.10;0.20<ΣAT/ΣCT<0.95

According to another aspect of the present disclosure, a micro imagingsystem comprising, in order from an object side to an image side: afirst lens element; a second lens element having positive refractivepower; and a third lens element having negative refractive power;wherein the micro imaging system has a total of three lens elements; acentral thickness of the first lens element is CT1, a central thicknessof the second lens element is CT2, an axial distance between the firstlens element and the second lens element is T12, an axial distancebetween an object-side surface of the first lens element and an imagesurface is TL, a focal length of the micro imaging system is f, acurvature radius of an object-side surface of the second lens element isR3, a curvature radius of an image-side surface of the second lenselement is R4, and the following conditions are satisfied:0.10<CT2/CT1<2.50;0.10<T12/CT1<3.80;3.80<TL/f<10.0;0<(R3−R4)/(R3+R4)<3.0.

According to another aspect of the present disclosure, an imagingapparatus includes the aforementioned micro imaging system and an imagesensor disposed on an image surface of the micro imaging system.

According to yet another aspect of the present disclosure, an electronicdevice includes the aforementioned imaging apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of an imaging apparatus according to the 1stembodiment of the present disclosure;

FIG. 1B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the1st embodiment;

FIG. 2A is a schematic view of an imaging apparatus according to the 2ndembodiment of the present disclosure;

FIG. 2B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the2nd embodiment;

FIG. 3A is a schematic view of an imaging apparatus according to the 3rdembodiment of the present disclosure;

FIG. 3B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the3rd embodiment;

FIG. 4A is a schematic view of an imaging apparatus according to the 4thembodiment of the present disclosure;

FIG. 4B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the4th embodiment;

FIG. 5A is a schematic view of an imaging apparatus according to the 5thembodiment of the present disclosure;

FIG. 5B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the5th embodiment;

FIG. 6A is a schematic view of an imaging apparatus according to the 6thembodiment of the present disclosure;

FIG. 6B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the6th embodiment;

FIG. 7A is a schematic view of an imaging apparatus according to the 7thembodiment of the present disclosure;

FIG. 7B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the7th embodiment;

FIG. 8A is a schematic view of an imaging apparatus according to the 8thembodiment of the present disclosure;

FIG. 8B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the8th embodiment;

FIG. 9A is a schematic view of an imaging apparatus according to the 9thembodiment of the present disclosure;

FIG. 9B shows longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the9th embodiment;

FIG. 10A is a schematic view of an imaging apparatus according to the10th embodiment of the present disclosure;

FIG. 10B shows longitudinal spherical aberration curves, astigmaticfield curves and a distortion curve of the imaging apparatus accordingto the 10th embodiment;

FIG. 11A is a schematic view of an imaging apparatus according to the11th embodiment of the present disclosure;

FIG. 11B shows longitudinal spherical aberration curves, astigmaticfield curves and a distortion curve of the imaging apparatus accordingto the 11th embodiment;

FIG. 12 is a schematic view showing distances represented by theparameters Yp32 of a micro imaging system of the present disclosure;

FIG. 13A shows a smartphone with an imaging apparatus of the presentdisclosure installed therein;

FIG. 13B shows a tablet with an imaging apparatus of the presentdisclosure installed therein;

FIG. 13C shows a wearable device with an imaging apparatus of thepresent disclosure installed therein;

FIG. 14A shows a rear view camera with an imaging apparatus of thepresent disclosure installed therein;

FIG. 14B shows a driving recording system with an imaging apparatus ofthe present disclosure installed therein; and

FIG. 14C shows a surveillance camera with an imaging apparatus of thepresent disclosure installed therein.

DETAILED DESCRIPTION

The present disclosure provides a micro imaging system including, inorder from an object side to an image side, a first lens element, asecond lens element, and a third lens element.

The first lens element may have negative refractive power so as tofavorably form a retro-focus structure to provide an image capturingrange with a wider angle of view. The first lens element may have animage-side surface being concave in a paraxial region thereof such thatthe first lens element may have sufficient diverging power to favorablyachieve a wide angle feature.

The second lens element has positive refractive power to provide themicro imaging system with a major portion of its converging power so asto balance aberrations caused by the first lens element and satisfy theneeds for miniaturization and a wide angle of view. The second lenselement may have an object-side surface being convex in a paraxialregion thereof such that the curvatures of the second lens element canbe effectively arranged to avoid excessive aberrations caused by theoverly large curvature. The second lens element may have an image-sidesurface being convex in a paraxial region so as to enhance theconvergent ability of the micro imaging system and properly allocate theposition of the principal point to achieve better imaging performance.

The third lens element has negative refractive power so as to favorablycontrol the back focal length of the micro imaging system to avoid anovercorrection of Petzval field. The third lens element may have both anobject-side surface and an image-side surface being aspheric. Theobject-side surface may be concave in a paraxial region thereof toadjust the incident angle of light on the surface to reduce theprobability of total reflections. The third lens element may have theimage-side surface being convex in a paraxial region thereof to controlthe incident angle of light on the image surface so as to have asufficiently large light retrieving area. The third lens element mayhave at least one concave shape between the paraxial region and anoff-axial region of the image-side surface thereof so as to favorablycorrect Petzval field to improve image quality in the off-axial region.

The micro imaging system has a total of three lens elements; at leastone surface of the first lens element, the second lens element and thethird lens element has at least one inflection point thereon so as toeffectively control the shape of the lens element in an off-axial regionand adjust the angle between the lens element and the light to avoidstray light.

When a central thickness of the first lens element is CT1, a centralthickness of the second lens element is CT2, and the following conditionis satisfied: 0.10<CT2/CT1<2.50, the structural properties can bestrengthened and the resistance to stress can be improved to avoiddeformation of lens elements caused by external forces or environmentalfactors so as to obtain better adaptability to the environment forvarious application. Preferably, the following condition can besatisfied: 0.10<CT2/CT1<1.80. Preferably, the following condition can besatisfied: 0.10<CT2/CT1<1.10.

When an axial distance between the first lens element and the secondlens element is T12, a focal length of the micro imaging system is f,and the following condition is satisfied: 0.45<T12/f<5.0, the distancebetween the first lens element and the second lens element can beeffectively controlled to avoid a waste of space from overly largespacing or reduction of the view angle from overly small spacing.Preferably, the following condition can be satisfied: 0.60<T12/f<3.5.

When a curvature radius of the object-side surface of the third lenselement is R5, a curvature radius of the image-side surface of the thirdlens element is R6, and the following condition is satisfied:|R5/R6|<0.70, the curvature of the third lens element can be properlyarranged so as to obtain an effective balance between the view angle andthe total track length. Preferably, the following condition can besatisfied: |R5/R6|<0.50.

When a focal length of the first lens element is f1, a focal length ofthe second lens element is f2, and the following condition is satisfied:−1.30<f2/f1<0.10, the distribution of the refractive power of the lenselements can be effectively balanced so as to obtain the features of awide view angle and miniaturization. Preferably, the following conditioncan be satisfied: −0.75<f2/f1<0.

When a sum of axial distances between every two adjacent lens elementsof the micro imaging system is ΣAT, a sum of central thicknesses of thefirst lens element, the second lens element, and the third lens elementis ΣCT, and the following condition is satisfied: 0.20<ΣAT/ΣCT<0.95, thespace of the micro imaging system can be effectively utilized to meetthe requirement of miniaturization.

When the axial distance between the first lens element and the secondlens element is T12, the central thickness of the first lens element isCT1, and the following condition is satisfied: 0.10<T12/CT1<3.80, thespace utilization of the micro imaging system can be improved to achieveminimization. Preferably, the following condition can be satisfied:0.30<T12/CT1<2.50.

When an axial distance between an object-side surface of the first lenselement and an image surface is TL, the focal length of the microimaging system is f, and the following condition is satisfied:3.80<TL/f<10.0, it is favorable for the micro imaging system to form thefeature of a wide angle of view and reduce the axial deviations of lightwith different wavelengths due to shifts from the optical axis.

When a curvature radius of the object-side surface of the second lenselement is R3, a curvature radius of the image-side surface of thesecond lens element is R4, and the following condition is satisfied:0<(R3−R4)/(R3+R4)<3.0, the geometry of the second lens element can beeffectively controlled and the position of the principal point is morefavorable to form a wide view angle system. Preferably, the followingcondition can be satisfied: 1.50<(R3−R4)/(R3+R4)<2.50.

When an Abbe number of the second lens element is V2, an Abbe number ofthe third lens element is V3, and the following condition is satisfied:2.0<V2/V3<4.0, aberrations of the micro imaging system can be correctedso as to favor the convergence of light with different wavelengths onthe same image surface.

When the axial distance between the first lens element and the secondlens element is T12, an axial distance between the second lens elementand the third lens element is T23, the central thickness of the firstlens element is CT1, and the following condition is satisfied:0.10<(T12+T23)/CT1<2.15, the lens spacing can be balanced so as to avoidinterference between the lens elements due to the small spacing orincreased stray light due to the large spacing. Preferably, thefollowing condition can be satisfied: 0.20<(T12+T23)/CT1<1.85.Preferably, the following condition can be satisfied:0.30<(T12+T23)/CT1<1.50.

When the curvature radius of the image-side surface of the second lenselement is R4, the central thickness of the second lens element is CT2,and the following condition is satisfied: −0.50<R4/CT2<0 degrees, therefractive power of the second lens element can be strengthened suchthat the micro imaging system can control the total track length withsufficient convergent ability.

When the focal length of the micro imaging system is f, the focal lengthof the second lens element is f2, and the following condition issatisfied: 0<f/f2<2.0, the main refractive power of the micro imagingsystem can be balanced while ensuring a sufficient field of view.

When the curvature radius of the image-side surface of the second lenselement is R4, the curvature radius of the object-side surface of thethird lens element is R5, and the following condition is satisfied:−100<(R4+R5)/(R4−R5)<−5.0, the spatial relationship between the secondlens element and the third lens element can be balanced such that highmanufacturability can be satisfied with an excellent aberrationcorrecting ability.

When a maximum image height of the micro imaging system is ImgH, thefocal length of the micro imaging system is f, and the followingcondition is satisfied: 0.95<ImgH/f<3.0, the light retrieving area ofthe micro imaging system and the image brightness can be increased whileimproving the symmetry of the micro imaging system to correctaberrations.

The micro imaging system may further comprise an aperture stop betweenthe first lens element and the second lens element. When an axialdistance between the aperture stop and the image-side surface of thethird lens element is SD, an axial distance between an object-sidesurface of the first lens element and the image-side surface of thethird lens element is TD, and the following condition is satisfied:0.10<SD/TD<0.50, the total track length of the micro imaging system canbe controlled while having an image capturing range with a large viewangle.

When a vertical distance between an inflection point on the image-sidesurface of the third lens element and an optical axis is Yp32 (Pleaserefer to FIG. 12, if there is a plurality of inflection points, Yp32 canbe one of the vertical distances between an inflection point on theimage-side surface of the third lens element and an optical axis isYp321 or Yp322), the focal length of the micro imaging system is f, andthe following condition is satisfied: 0<Yp32/f<1.50, the aberrations inan off-axial region of the micro imaging system can be corrected so asto effectively reduce coma aberrations and distortions.

When a focal length of the third lens element is f3, the focal length ofthe first lens element is f1, and the following condition is satisfied:0.1<f3/f1<0.95, the functionality of the third lens element can beimproved for aberration corrections.

According to the micro imaging system of the present disclosure, thelens elements thereof can be made of glass or plastic material. When thelens elements are made of glass material, the distribution of therefractive power of the micro imaging system may be more flexible todesign. When the lens elements are made of plastic material, themanufacturing cost can be effectively reduced. Furthermore, surfaces ofeach lens element can be arranged to be aspheric (ASP). Since theseaspheric surfaces can be easily formed into shapes other than sphericalshapes so as to have more controllable variables for eliminatingaberrations and to further decrease the required quantity of lenselements, the total track length of the micro imaging system can beeffectively reduced.

According to the micro imaging system of the present disclosure, themicro imaging system can include at least one stop, such as an aperturestop, a glare stop or a field stop, so as to favorably reduce the amountof stray light and thereby improving the image quality.

According to the micro imaging system of the present disclosure, anaperture stop can be configured as a front stop or a middle stop. Afront stop disposed between an imaged object and the first lens elementcan provide a longer distance between the exit pupil and the imagesurface so that there is a telecentric effect for improving theimage-sensing efficiency of an image sensor, such as a CCD or CMOSsensor. A middle stop disposed between the first lens element and theimage surface is favorable for enlarging the field of view, therebyproviding the micro imaging system with the advantage of a wide-anglelens.

According to the micro imaging system of the present disclosure, whenthe lens element has a convex surface and the region of convex shape isnot defined, it indicates that the surface can be convex in the paraxialregion thereof. When the lens element has a concave surface and theregion of concave shape is not defined, it indicates that the surfacecan be concave in the paraxial region thereof. Likewise, when the regionof refractive power or focal length of a lens element is not defined, itindicates that the region of refractive power or focal length of thelens element can be in the paraxial region thereof.

According to the micro imaging system of the present disclosure, theimage surface of the micro imaging system, based on the correspondingimage sensor, can be a plane or a curved surface with an arbitrarycurvature, especially a curved surface being concave facing towards theobject side.

The micro imaging system of the present disclosure can be optionallyapplied to moving focus optical systems. According to the micro imagingsystem of the present disclosure, the micro imaging system features agood aberration correction capability and high image quality, and can beapplied to electronic devices such as smart electronics, medicaldevices, precision instruments, car devices, recognition devices,entertainment devices, sports devices and smart home systems.

According to the present disclosure, an imaging apparatus includes theaforementioned micro imaging system and an image sensor, wherein theimage sensor is disposed on or near an image surface of the microimaging system. Therefore, the design of the micro imaging systemenables the imaging apparatus to achieve high image quality. Preferably,the micro imaging system can further include a barrel member, a holdermember or a combination thereof. In addition, the imaging apparatus canfurther include an optical image stabilizer (OIS) to enhance the microimaging system with even better imaging quality.

Please refer to FIG. 13A, FIG. 13B and FIG. 13C, an imaging apparatus1301 may be installed in an electronic device including, but not limitedto, a smartphone 1310, a tablet 1320, or a wearable device 1330. Also,please refer to FIG. 14A, FIG. 14B and FIG. 14C, an imaging apparatus1401 (optionally with a display screen 1402) may be installed in anelectronic device including, but not limited to, a rear view camera1410, a driving recording system 1420, or a surveillance camera 1430.The above figures of different electronic devices are only exemplary forshowing the imaging apparatus of the present disclosure installed in anelectronic device, and the present disclosure is not limited thereto.Preferably, the electronic device can further include a control unit, adisplay unit, a storage unit, a random access memory unit (RAM) or acombination thereof.

According to the above description of the present disclosure, thefollowing 1st-11th specific embodiments are provided for furtherexplanation.

1st Embodiment

FIG. 1A is a schematic view of an imaging apparatus according to the 1stembodiment of the present disclosure. FIG. 1B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the1st embodiment.

In FIG. 1A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor160. The micro imaging system includes, in order from an object side toan image side, a first lens element 110, an aperture stop 100, a secondlens element 120, and a third lens element 130.

The first lens element 110 with negative refractive power has anobject-side surface 111 being concave in a paraxial region thereof, animage-side surface 112 being concave in a paraxial region thereof, boththe object-side surface 111 and the image-side surface 112 beingaspheric, and one inflection point on the object-side surface 111. Thefirst lens element 110 is made of plastic material.

The second lens element 120 with positive refractive power has anobject-side surface 121 being convex in a paraxial region thereof, animage-side surface 122 being convex in a paraxial region thereof, andboth the object-side surface 121 and the image-side surface 122 beingaspheric. The second lens element 120 is made of plastic material.

The third lens element 130 with negative refractive power has anobject-side surface 131 being concave in a paraxial region thereof, animage-side surface 132 being convex in a paraxial region thereof, boththe object-side surface 131 and the image-side surface 132 beingaspheric, two inflection points on the object-side surface 131, and twoinflection points on the image-side surface 132. The third lens element130 is made of plastic material.

The micro imaging system further includes an IR cut filter 140 locatedbetween the third lens element 130 and an image surface 150. The IR cutfilter 140 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 160 is disposed onor near the image surface 150 of the micro imaging system.

The detailed optical data of the 1st embodiment are shown in TABLE 1,and the aspheric surface data are shown in TABLE 2, wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 1 (1st Embodiment) f = 0.24 mm, Fno = 3.00, HFOV = 69.0 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 −10.693 ASP 0.400 Plastic 1.544 56.0 −0.402 0.223 ASP 0.400 3 Ape. Stop Plano 0.020 4 Lens 2 0.421 ASP 0.288Plastic 1.544 56.0 0.22 5 −0.125 ASP 0.035 6 Lens 3 −0.178 ASP 0.200Plastic 1.671 19.5 −0.48 7 −0.572 ASP 0.060 8 IR Cut Filter Plano 0.400Glass 1.517 64.2 — 9 Plano 0.044 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 2 Aspheric Coefficients Surface # 1 2 4 5 6 7 k = −9.0000E+01−3.1239E−01  8.9435E−01 −6.9023E−01 −3.0378E+00  2.8622E+00 A4 = 1.5578E−01 −3.3874E+01 −2.6977E+01  2.0211E+02  2.0421E+02  1.0722E+02A6 =  4.3531E+02  4.5203E+03 −1.1174E+04 −1.4298E+04 −3.4559E+03 A8 =−3.3015E+03 −4.9023E+05  3.9638E+05  4.9346E+05  6.1057E+04 A10 =−3.3733E+03  2.2714E+07 −7.2517E+06 −9.1160E+06 −5.6309E+05 A12 =−3.4365E+08  5.5593E+07  6.8322E+07  2.1876E+06

The equation of the aspheric surface profiles is expressed as follows:

${X(Y)} = {{\left( {Y^{2}\text{/}R} \right)\text{/}\left( {1 + {{sqrt}\left( {1 - {\left( {1 + k} \right)*\left( {Y\text{/}R} \right)^{2}}} \right)}} \right)} + {\sum\limits_{i}{({Ai})*\left( Y^{i} \right)}}}$

where:

X is the relative distance between a point on the aspheric surfacespaced at a distance Y from the optical axis and the tangential plane atthe aspheric surface vertex on the optical axis;

Y is the vertical distance from the point on the aspheric surfaceprofile to the optical axis;

R is the curvature radius;

k is the conic coefficient; and

Ai is the i-th aspheric coefficient.

In the 1st embodiment, a focal length of the micro imaging system is f,an f-number of the micro imaging system is Fno, a half of a maximalfield of view of the micro imaging system is HFOV, and these parametershave the following values: f=0.24 mm; Fno=3.00; and HFOV=69.0 degrees.

In the 1st embodiment, an Abbe number of the second lens element 120 isV2, an Abbe number of the third lens element 130 is V3, and they satisfythe condition: V2/V3=2.87.

In the 1st embodiment, a central thickness of the first lens element 110is CT1, a central thickness of the second lens element 120 is CT2, andthey satisfy the condition: CT2/CT1=0.72.

In the 1st embodiment, the central thickness of the first lens element110 is CT1, an axial distance between the first lens element 110 and thesecond lens element 120 is T12, and they satisfy the condition:T12/CT1=1.05.

In the 1st embodiment, the axial distance between the first lens element110 and the second lens element 120 is T12, the focal length of themicro imaging system is f, and they satisfy the condition: T12/f=1.77.

In the 1st embodiment, the axial distance between the first lens element110 and the second lens element 120 is T12, an axial distance betweenthe second lens element 120 and the third lens element 130 is T23, thecentral thickness of the first lens element is CT1, and they satisfy thecondition: (T12+T23)/CT1=1.14.

In the 1st embodiment, a curvature radius of the object-side surface 121of the second lens element 120 is R3, a curvature radius of theimage-side surface 122 of the second lens element 120 is R4, and theysatisfy the condition: (R3−R4)/(R3+R4)=1.84.

In the 1st embodiment, the curvature radius of the image-side surface122 of the second lens element 120 is R4, a curvature radius of theobject-side surface 131 of the third lens element 130 is R5, and theysatisfy the condition: (R4+R5)/(R4−R5)=−5.71.

In the 1st embodiment, the curvature radius of the image-side surface122 of the second lens element 120 is R4, the central thickness of thesecond lens element 120 is CT2, and they satisfy the condition:R4/CT2=−0.43.

In the 1st embodiment, the curvature radius of the object-side surface131 of the third lens element 130 is R5, a curvature radius of theimage-side surface 132 of the third lens element 130 is R6, and theysatisfy the condition: |R5/R6|=0.31.

In the 1st embodiment, a focal length of the first lens element 110 isf1, a focal length of the second lens element 120 is f2, and theysatisfy the condition: f2/f1=−0.55.

In the 1st embodiment, the focal length of the micro imaging system isf, the focal length of the second lens element 120 is f2, and theysatisfy the condition: f/f2=1.09.

In the 1st embodiment, a sum of axial distances between every twoadjacent lens elements of the micro imaging system is ΣAT, a sum ofcentral thicknesses of the first lens element 110, the second lenselement 120, and the third lens element 130 is ΣCT, and they satisfy thecondition: ΣAT/ΣCT=0.51.

In the 1st embodiment, an axial distance between the object-side surface111 of the first lens element 110 and the image surface 150 is TL, thefocal length of the micro imaging system is f, and they satisfy thecondition: TL/f=7.79.

In the 1st embodiment, a maximum image height of the micro imagingsystem is ImgH (that is, a half of the diagonal length of an effectivesensing area of the image sensor 160), the focal length of the microimaging system is f, and they satisfy the condition: ImgH/f=2.09.

In the 1st embodiment, an axial distance between the aperture stop 100and the image-side surface 132 of the third lens element 130 is SD, anaxial distance between the object-side surface 111 of the first lenselement 110 and the image-side surface 132 of the third lens element 130is TD, and they satisfy the condition: SD/TD=0.40.

In the 1st embodiment, a vertical distance between an inflection pointon the image-side surface 132 of the third lens element 130 and anoptical axis is Yp32, the focal length of the micro imaging system is f.Since there are two inflection points on the image-side surface 132 ofthe third lens element 130, they satisfy the condition: Yp32/f=0.13 andYp32/f=0.76, respectively.

2nd Embodiment

FIG. 2A is a schematic view of an imaging apparatus according to the 2ndembodiment of the present disclosure. FIG. 2B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the2nd embodiment.

In FIG. 2A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor260. The micro imaging system includes, in order from an object side toan image side, a first lens element 210, an aperture stop 200, a secondlens element 220, and a third lens element 230.

The first lens element 210 with negative refractive power has anobject-side surface 211 being concave in a paraxial region thereof, animage-side surface 212 being concave in a paraxial region thereof, boththe object-side surface 211 and the image-side surface 212 beingaspheric, and one inflection point on the object-side surface 211. Thefirst lens element 210 is made of plastic material.

The second lens element 220 with positive refractive power has anobject-side surface 221 being convex in a paraxial region thereof, animage-side surface 222 being convex in a paraxial region thereof, andboth the object-side surface 221 and the image-side surface 222 beingaspheric. The second lens element 220 is made of plastic material.

The third lens element 230 with negative refractive power has anobject-side surface 231 being concave in a paraxial region thereof, animage-side surface 232 being concave in a paraxial region thereof, boththe object-side surface 231 and the image-side surface 232 beingaspheric, and two inflection points on the object-side surface 231. Thethird lens element 230 is made of plastic material.

The micro imaging system further includes an IR cut filter 240 locatedbetween the third lens element 230 and an image surface 250. The IR cutfilter 240 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 260 is disposed onor near the image surface 250 of the micro imaging system.

The detailed optical data of the 2nd embodiment are shown in TABLE 3,and the aspheric surface data are shown in TABLE 4, wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 3 (2nd Embodiment) f = 0.42 mm, Fno = 4.38, HFOV = 54.1 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 −2.500 ASP 0.544 Plastic 1.534 55.9 −0.782 0.535 ASP 0.285 3 Ape. Stop Plano 0.020 4 Lens 2 0.421 ASP 0.294Plastic 1.544 56.0 0.22 5 −0.124 ASP 0.044 6 Lens 3 −0.174 ASP 0.200Plastic 1.639 23.5 −0.24 7 2.250 ASP 0.100 8 IR Cut Filter Plano 0.300Glass 1.517 64.2 — 9 Plano 0.063 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 4 Aspheric Coefficients Surface # 1 2 4 5 6 7 k = 1.0000E+01−6.3071E+00  3.7751E−01 −6.9208E−01 −2.9057E+00 −9.1152E+00 A4 =1.5742E−01  4.6494E+00 −1.0674E+01  1.8674E+02  2.0181E+02  6.2161E+01A6 = 4.6365E−01  1.1339E+02  1.2870E+03 −1.0097E+04 −1.5712E+04−2.2715E+03 A8 = −3.4016E+03 −2.7603E+05  3.8941E+05  6.6945E+05 4.5195E+04 A10 =  6.6319E+04  1.7062E+07 −8.8089E+06 −1.6395E+07−4.8884E+05 A12 = −2.9941E+08  8.9662E+07  1.6718E+08  2.2576E+06

In the 2nd embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 2nd embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 3 and TABLE 4and satisfy the conditions stated in table below.

2nd Embodiment f [mm] 0.42 R4/CT2 −0.42 Fno. 4.38 |R5/R6| 0.08 HFOV[deg.] 54.1 f2/f1 −0.28 V2/V3 2.38 f/f2 1.92 CT2/CT1 0.54 ΣAT/ΣCT 0.34T12/CT1 0.56 TL/f 4.43 T12/f 0.73 ImgH/f 1.19 (T12 + T23)/CT1 0.64 SD/TD0.40 (R3 − R4)/(R3 + R4) 1.84 Yp32/f — (R4 + R5)/(R4 − R5) −6.00

3rd Embodiment

FIG. 3A is a schematic view of an imaging apparatus according to the 3rdembodiment of the present disclosure. FIG. 3B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the3rd embodiment.

In FIG. 3A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor360. The micro imaging system includes, in order from an object side toan image side, a first lens element 310, an aperture stop 300, a secondlens element 320, and a third lens element 330.

The first lens element 310 with negative refractive power has anobject-side surface 311 being convex in a paraxial region thereof, animage-side surface 312 being concave in a paraxial region thereof, andboth the object-side surface 311 and the image-side surface 312 beingaspheric. The first lens element 310 is made of plastic material.

The second lens element 320 with positive refractive power has anobject-side surface 321 being convex in a paraxial region thereof, animage-side surface 322 being convex in a paraxial region thereof, andboth the object-side surface 321 and the image-side surface 322 beingaspheric. The second lens element 320 is made of plastic material.

The third lens element 330 with negative refractive power has anobject-side surface 331 being concave in a paraxial region thereof, animage-side surface 332 being concave in a paraxial region thereof, andboth the object-side surface 331 and the image-side surface 332 beingaspheric. The third lens element 330 is made of plastic material.

The micro imaging system further includes an IR cut filter 340 locatedbetween the third lens element 330 and an image surface 350. The IR cutfilter 340 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 360 is disposed onor near the image surface 350 of the micro imaging system.

The detailed optical data of the 3rd embodiment are shown in TABLE 5,and the aspheric surface data are shown in TABLE 6, wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 5 (3rd Embodiment) f = 0.40 mm, Fno = 4.14, HFOV = 55.9 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 19.531 ASP 0.494 Plastic 1.534 55.9 −0.612 0.320 ASP 0.314 3 Ape. Stop Plano 0.020 4 Lens 2 0.421 ASP 0.292Plastic 1.544 56.0 0.22 5 −0.124 ASP 0.048 6 Lens 3 −0.170 ASP 0.200Plastic 1.639 23.5 −0.27 7 91.766 ASP 0.100 8 IR Cut Filter Plano 0.300Glass 1.517 64.2 — 9 Plano 0.084 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 6 Aspheric Coefficients Surface # 1 2 4 5 6 7 k = −8.9992E+01−2.0282E+00 −9.2593E−02 −6.9411E−01 −2.4737E+00 −9.0000E+01 A4 = 7.7194E−02  2.1930E+00 −1.4863E+01  1.6763E+02  1.8685E+02  5.4221E+01A6 =  5.9844E−02  5.2070E+02  1.8942E+03 −8.6477E+03 −1.3671E+04−1.8464E+03 A8 = −1.4008E+04 −3.3686E+05  3.2399E+05  5.3793E+05 3.3827E+04 A10 =  1.7784E+05  1.9856E+07 −6.9445E+06 −1.1990E+07−3.3226E+05 A12 = −3.4357E+08  6.5415E+07  1.0958E+08  1.3647E+06

In the 3rd embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 3rd embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 5 and TABLE 6and satisfy the conditions stated in table below.

3rd Embodiment f [mm] 0.40 R4/CT2 −0.42 Fno. 4.14 |R5/R6| 0.002 HFOV[deg.] 55.9 f2/f1 −0.35 V2/V3 2.38 f/f2 1.83 CT2/CT1 0.59 ΣAT/ΣCT 0.39T12/CT1 0.68 TL/f 4.66 T12/f 0.84 ImgH/f 1.25 (T12 + T23)/CT1 0.77 SD/TD0.41 (R3 − R4)/(R3 + R4) 1.83 Yp32/f — (R4 + R5)/(R4 − R5) −6.31

4th Embodiment

FIG. 4A is a schematic view of an imaging apparatus according to the 4thembodiment of the present disclosure. FIG. 4B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the4th embodiment.

In FIG. 4A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor460. The micro imaging system includes, in order from an object side toan image side, a first lens element 410, an aperture stop 400, a secondlens element 420, and a third lens element 430.

The first lens element 410 with negative refractive power has anobject-side surface 411 being convex in a paraxial region thereof, animage-side surface 412 being concave in a paraxial region thereof, andboth the object-side surface 411 and the image-side surface 412 beingaspheric. The first lens element 410 is made of plastic material.

The second lens element 420 with positive refractive power has anobject-side surface 421 being convex in a paraxial region thereof, animage-side surface 422 being convex in a paraxial region thereof, andboth the object-side surface 421 and the image-side surface 422 beingaspheric. The second lens element 420 is made of plastic material.

The third lens element 430 with negative refractive power has anobject-side surface 431 being concave in a paraxial region thereof, animage-side surface 432 being convex in a paraxial region thereof, boththe object-side surface 431 and the image-side surface 432 beingaspheric, and three inflection points on the image-side surface 432. Thethird lens element 430 is made of plastic material.

The micro imaging system further includes an IR cut filter 440 locatedbetween the third lens element 430 and an image surface 450. The IR cutfilter 440 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 460 is disposed onor near the image surface 450 of the micro imaging system.

The detailed optical data of the 4th embodiment are shown in TABLE 7,and the aspheric surface data are shown in TABLE 8, wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 7 (4th Embodiment) f = 0.42 mm, Fno = 4.37, HFOV = 57.1 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 16.409 ASP 0.385 Plastic 1.583 30.2 −0.782 0.440 ASP 0.399 3 Ape. Stop Plano 0.020 4 Lens 2 0.409 ASP 0.312Plastic 1.530 55.8 0.23 5 −0.125 ASP 0.060 6 Lens 3 −0.144 ASP 0.200Plastic 1.660 20.4 −0.26 7 −1.389 ASP 0.100 8 IR Cut Filter Plano 0.300Glass 1.517 64.2 — 9 Plano 0.065 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

Aspheric Coefficients Surface # 1 2 4 5 6 7 k = −9.0000E+01 −9.5036E−01−1.4221E−01 −7.0744E−01 −1.7929E+00  1.9995E+01 A4 =  3.1637E−01 9.7710E−01 −1.3380E+01  1.3535E+02  1.6779E+02  4.9156E+01 A6 =−1.0874E−01  1.3912E+02  6.7014E+02 −6.1339E+03 −1.1034E+04 −1.4491E+03A8 = −2.3678E+03 −4.4778E+04  2.2799E+05  3.8436E+05  2.2913E+04 A10 = 2.5893E+04 −6.5184E+05 −5.0810E+06 −7.7135E+06 −1.9137E+05 A12 = 1.6072E+08  5.2662E+07  6.6375E+07  6.8220E+05

In the 4th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 4th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 7 and TABLE 8and satisfy the conditions stated in table below.

4th Embodiment f [mm] 0.42 R4/CT2 −0.40 Fno. 4.37 |R5/R6| 0.10 HFOV[deg.] 57.1 f2/f1 −0.29 V2/V3 2.73 f/f2 1.85 CT2/CT1 0.81 ΣAT/ΣCT 0.53T12/CT1 1.09 TL/f 4.41 T12/f 1.00 ImgH/f 1.19 (T12 + T23)/CT1 1.25 SD/TD0.43 (R3 − R4)/(R3 + R4) 1.88 Yp32/f 0.07/0.41/0.62 (R4 + R5)/(R4 − R5)−14.16

5th Embodiment

FIG. 5A is a schematic view of an imaging apparatus according to the 5thembodiment of the present disclosure. FIG. 5B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the5th embodiment.

In FIG. 5A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor560. The micro imaging system includes, in order from an object side toan image side, a first lens element 510, an aperture stop 500, a secondlens element 520, and a third lens element 530.

The first lens element 510 with negative refractive power has anobject-side surface 511 being convex in a paraxial region thereof, animage-side surface 512 being concave in a paraxial region thereof, boththe object-side surface 511 and the image-side surface 512 beingaspheric, and one inflection point on the object-side surface 511. Thefirst lens element 510 is made of plastic material.

The second lens element 520 with positive refractive power has anobject-side surface 521 being convex in a paraxial region thereof, animage-side surface 522 being convex in a paraxial region thereof, boththe object-side surface 521 and the image-side surface 522 beingaspheric, one inflection point on the object-side surface 521 and oneinflection point on the image-side surface 522. The second lens element520 is made of plastic material.

The third lens element 530 with negative refractive power has anobject-side surface 531 being concave in a paraxial region thereof, animage-side surface 532 being convex in a paraxial region thereof, boththe object-side surface 531 and the image-side surface 532 beingaspheric, one inflection point on the object-side surface 531 and fourinflection points on the image-side surface 532. The third lens element530 is made of plastic material.

The micro imaging system further includes an IR cut filter 540 locatedbetween the third lens element 530 and an image surface 550. The IR cutfilter 540 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 560 is disposed onor near the image surface 550 of the micro imaging system.

The detailed optical data of the 5th embodiment are shown in TABLE 9,and the aspheric surface data are shown in TABLE 10, wherein the unitsof the curvature radius, the thickness and the focal length areexpressed in mm, and HFOV is a half of the maximal field of view.

TABLE 9 (5th Embodiment) f = 0.32 mm, Fno = 3.40, HFOV = 57.1 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 3.938 ASP 0.336 Plastic 1.535 56.3 −0.72 20.340 ASP 0.609 3 Ape. Stop Plano 0.020 4 Lens 2 0.419 ASP 0.344 Plastic1.530 55.8 0.23 5 −0.124 ASP 0.056 6 Lens 3 −0.146 ASP 0.200 Plastic1.660 20.4 −0.28 7 −1.141 ASP 0.060 8 IR Cut Filter Plano 0.300 Glass1.517 64.2 — 9 Plano 0.059 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 10 Aspheric Coefficients Surface # 1 2 4 k= 1.9813E+01 −1.2251E+00−7.1874E−01 A4= 1.0647E+00 3.5906E+00 −4.6035E+01 A6= −1.0299E+008.8075E+01 1.1487E+04 A8= −6.5988E+02 −1.7997E+06 A10= 3.8522E+031.2983E+08 A12= −3.4559E+09 Surface # 5 6 7 k= −7.0617E−01 −1.6563E+001.0065E+01 A4= 1.1651E+02 1.4179E+02 3.5721E+01 A6= −4.1668E+03−8.4634E+03 −8.3211E+02 A8= 1.3606E+05 2.7981E+05 1.0525E+04 A10=−2.7971E+06 −5.4777E+06 −7.1092E+04 A12= 2.7754E+07 4.4608E+072.0669E+05

In the 5th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 5th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 9 and TABLE 10and satisfy the conditions stated in table below.

5th Embodiment f [mm] 0.32 R4/CT2 −0.36 Fno. 3.40 |R5/R6| 0.13 HFOV[deg.] 57.1 f2/f1 −0.32 V2/V3 2.73 f/f2 1.39 CT2/CT1 1.02 ΣAT/ΣCT 0.78T12/CT1 1.87 TL/f 6.18 T12/f 1.96 ImgH/f 1.54 (T12 + T23)/CT1 2.04 SD/TD0.40 (R3 − R4)/(R3 + R4) 1.84 Yp32/f 0.12/0.56/0.93/1.00 (R4 + R5)/(R4 −R5) −11.87

6th Embodiment

FIG. 6A is a schematic view of an imaging apparatus according to the 6thembodiment of the present disclosure. FIG. 6B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the6th embodiment.

In FIG. 6A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor660. The micro imaging system includes, in order from an object side toan image side, a first lens element 610, an aperture stop 600, a secondlens element 620, and a third lens element 630.

The first lens element 610 with negative refractive power has anobject-side surface 611 being convex in a paraxial region thereof, animage-side surface 612 being concave in a paraxial region thereof, andboth the object-side surface 611 and the image-side surface 612 beingaspheric. The first lens element 610 is made of plastic material.

The second lens element 620 with positive refractive power has anobject-side surface 621 being convex in a paraxial region thereof, animage-side surface 622 being convex in a paraxial region thereof, andboth the object-side surface 621 and the image-side surface 622 beingaspheric. The second lens element 620 is made of plastic material.

The third lens element 630 with negative refractive power has anobject-side surface 631 being concave in a paraxial region thereof, animage-side surface 632 being convex in a paraxial region thereof, boththe object-side surface 631 and the image-side surface 632 beingaspheric, two inflection points on the object-side surface 631 and oneinflection point on the image-side surface 632. The third lens element630 is made of plastic material.

The micro imaging system further includes an IR cut filter 640 locatedbetween the third lens element 630 and an image surface 650. The IR cutfilter 640 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 660 is disposed onor near the image surface 650 of the micro imaging system.

The detailed optical data of the 6th embodiment are shown in TABLE 11,and the aspheric surface data are shown in TABLE 12, wherein the unitsof the curvature radius, the thickness and the focal length areexpressed in mm, and HFOV is a half of the maximal field of view.

TABLE 11 (6th Embodiment) f = 0.70 mm, Fno = 3.60, HFOV = 56.0 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 10.000 1 Lens 1 1953.125 ASP 1.134 Plastic 1.534 55.9−1.07 2 0.571 ASP 0.684 3 Ape. Stop Plano 0.020 4 Lens 2 0.885 ASP 0.518Plastic 1.544 56.0 0.42 5 −0.243 ASP 0.102 6 Lens 3 −0.344 ASP 0.200Plastic 1.639 23.5 −0.54 7 −142.239 ASP 0.200 8 IR Cut Filter Plano0.600 Glass 1.517 64.2 — 9 Plano 0.240 10 Image Surface Plano — *Reference wavelength is d-line 587.6 nm.

TABLE 12 Aspheric Coefficients Surface # 1 2 4 k= −9.0000E+01−7.7581E−01 −5.1725E−01 A4= 8.2053E−02 1.1477E+00 −1.9631E+00 A6=−3.0430E−02 1.0698E+01 2.9451E+01 A8= 7.5035E−03 −7.3473E+01 −1.8451E+03A10= −9.0398E−04 3.1612E+02 3.2568E+04 A12= −1.5390E+05 Surface # 5 6 7k= −6.9383E−01 −3.2175E+00 2.0000E+01 A4= 1.9450E+01 2.3397E+019.5110E+00 A6= −2.4499E+02 −4.2308E+02 −1.0159E+02 A8= 2.3462E+034.1246E+03 5.9349E+02 A10= −1.3518E+04 −2.3182E+04 −1.8883E+03 A12=3.5358E+04 5.4663E+04 2.5435E+03

In the 6th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 6th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 11 and TABLE 12and satisfy the conditions stated in table below.

6th Embodiment f [mm] 0.70 R4/CT2 −0.47 Fno. 3.60 |R5/R6| 0.002 HFOV[deg.] 56.0 f2/f1 −0.39 V2/V3 2.38 f/f2 1.68 CT2/CT1 0.46 ΣAT/ΣCT 0.44T12/CT1 0.62 TL/f 5.27 T12/f 1.00 ImgH/f 1.41 (T12 + T23)/CT1 0.71 SD/TD0.32 (R3 − R4)/(R3 + R4) 1.76 Yp32/f 0.01 (R4 + R5)/(R4 − R5) −5.79

7th Embodiment

FIG. 7A is a schematic view of an imaging apparatus according to the 7thembodiment of the present disclosure. FIG. 7B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the7th embodiment.

In FIG. 7A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor760. The micro imaging system includes, in order from an object side toan image side, a first lens element 710, an aperture stop 700, a secondlens element 720, and a third lens element 730.

The first lens element 710 with negative refractive power has anobject-side surface 711 being concave in a paraxial region thereof, animage-side surface 712 being concave in a paraxial region thereof, boththe object-side surface 711 and the image-side surface 712 beingaspheric, and one inflection point on the object-side surface 711. Thefirst lens element 710 is made of plastic material.

The second lens element 720 with positive refractive power has anobject-side surface 721 being convex in a paraxial region thereof, animage-side surface 722 being convex in a paraxial region thereof, boththe object-side surface 721 and the image-side surface 722 beingaspheric, and one inflection point on the object-side surface 721. Thesecond lens element 720 is made of plastic material.

The third lens element 730 with negative refractive power has anobject-side surface 731 being concave in a paraxial region thereof, animage-side surface 732 being convex in a paraxial region thereof, boththe object-side surface 731 and the image-side surface 732 beingaspheric, one inflection point on the object-side surface 731 and threeinflection points on the image-side surface 732. The third lens element730 is made of plastic material.

The micro imaging system further includes an IR cut filter 740 locatedbetween the third lens element 730 and an image surface 750. The IR cutfilter 740 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 760 is disposed onor near the image surface 750 of the micro imaging system.

The detailed optical data of the 7th embodiment are shown in TABLE 13,and the aspheric surface data are shown in TABLE 14, wherein the unitsof the curvature radius, the thickness and the focal length areexpressed in mm, and HFOV is a half of the maximal field of view.

TABLE 13 (7th Embodiment) f = 0.72 mm, Fno = 3.18, HFOV = 56.0 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 10.000 1 Lens 1 −2.399 ASP 1.594 Plastic 1.535 56.3 −4.362 104.373 ASP 0.552 3 Ape. Stop Plano 0.022 4 Lens 2 1.093 ASP 0.530Plastic 1.535 56.3 0.41 5 −0.230 ASP 0.114 6 Lens 3 −0.262 ASP 0.232Plastic 1.671 19.5 −0.50 7 −1.651 ASP 0.200 8 IR Cut Filter Plano 0.300Glass 1.517 64.2 — 9 Plano 0.154 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 14 Aspheric Coefficients Surface # 1 2 4 k= −1.5094E+01 2.0000E+01−1.1911E+01 A4= 7.6990E−02 8.2794E−01 −2.8291E+00 A6= −1.8718E−021.4166E+00 1.2630E+02 A8= 2.0682E−03 −9.3411E+00 −5.2051E+03 A10=−6.5656E−05 1.5511E+01 6.6323E+04 A12= −2.5549E+05 Surface # 5 6 7 k=−6.9575E−01 −1.4860E+00 6.3991E+00 A4= 1.5564E+01 2.2279E+01 6.0486E+00A6= −1.4766E+02 −3.8591E+02 −5.7260E+01 A8= 9.9462E+02 3.3542E+032.6353E+02 A10= −3.5857E+03 −1.7757E+04 −6.4907E+02 A12= 5.4219E+034.1382E+04 6.8484E+02

In the 7th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 7th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 13 and TABLE 14and satisfy the conditions stated in table below.

7th Embodiment f [mm] 0.72 R4/CT2 −0.43 Fno. 3.18 |R5/R6| 0.16 HFOV[deg.] 56.0 f2/f1 −0.09 V2/V3 2.89 f/f2 1.75 CT2/CT1 0.33 ΣAT/ΣCT 0.29T12/CT1 0.36 TL/f 5.10 T12/f 0.79 ImgH/f 1.24 (T12 + T23)/CT1 0.43 SD/TD0.30 (R3 − R4)/(R3 + R4) 1.53 Yp32/f 0.14/0.32/0.72 (R4 + R5)/(R4 − R5)−15.46

8th Embodiment

FIG. 8A is a schematic view of an imaging apparatus according to the 8thembodiment of the present disclosure. FIG. 8B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the8th embodiment.

In FIG. 8A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor860. The micro imaging system includes, in order from an object side toan image side, a first lens element 810, an aperture stop 800, a secondlens element 820, and a third lens element 830.

The first lens element 810 with positive refractive power has anobject-side surface 811 being concave in a paraxial region thereof, animage-side surface 812 being convex in a paraxial region thereof, boththe object-side surface 811 and the image-side surface 812 beingaspheric, one inflection point on the object-side surface 811, and oneinflection point on the image-side surface 812. The first lens element810 is made of plastic material.

The second lens element 820 with positive refractive power has anobject-side surface 821 being convex in a paraxial region thereof, animage-side surface 822 being convex in a paraxial region thereof, boththe object-side surface 821 and the image-side surface 822 beingaspheric, and one inflection point on the object-side surface 821. Thesecond lens element 820 is made of plastic material.

The third lens element 830 with negative refractive power has anobject-side surface 831 being concave in a paraxial region thereof, animage-side surface 832 being convex in a paraxial region thereof, boththe object-side surface 831 and the image-side surface 832 beingaspheric, one inflection point on the object-side surface 831 and threeinflection points on the image-side surface 832. The third lens element830 is made of plastic material.

The micro imaging system further includes an IR cut filter 840 locatedbetween the third lens element 830 and an image surface 850. The IR cutfilter 840 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 860 is disposed onor near the image surface 850 of the micro imaging system.

The detailed optical data of the 8th embodiment are shown in TABLE 15,and the aspheric surface data are shown in TABLE 16, wherein the unitsof the curvature radius, the thickness and the focal length areexpressed in mm, and HFOV is a half of the maximal field of view.

TABLE 15 (8th Embodiment) f = 0.64 mm, Fno = 2.76, HFOV = 57.0 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 10.000 1 Lens 1 −1.260 ASP 1.645 Plastic 1.534 55.9 10.922 −1.506 ASP 0.686 3 Ape. Stop Plano 0.020 4 Lens 2 1.090 ASP 0.511Plastic 1.544 56.0 0.40 5 −0.228 ASP 0.071 6 Lens 3 −0.257 ASP 0.200Plastic 1.639 23.5 −0.50 7 −1.711 ASP 0.200 8 IR Cut Filter Plano 0.300Glass 1.517 64.2 — 9 Plano 0.117 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 16 Aspheric Coefficients Surface # 1 2 4 k= −8.9858E+00−2.3224E+01 −6.0319E+00 A4= 6.3348E−02 2.4219E−01 −1.7447E+00 A6=−1.8573E−02 −9.3895E−02 1.1304E+01 A8= 2.8706E−03 3.8686E−02 −2.3356E+02A10= −2.2077E−04 −1.8527E−01 −3.9178E+03 A12= 6.9965E−06 1.8539E−013.7261E+04 Surface # 5 6 7 k= −7.4618E−01 −1.4085E+00 7.7767E+00 A4=1.7655E+01 2.0282E+01 5.8881E+00 A6= −1.9245E+02 −3.2840E+02 −6.0670E+01A8= 1.2620E+03 1.8996E+03 2.7881E+02 A10= −3.9123E+03 −4.6843E+03−6.6790E+02 A12= 2.6279E+03 4.9005E+03 7.2639E+02

In the 8th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 8th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 15 and TABLE 16and satisfy the conditions stated in table below.

8th Embodiment f [mm] 0.64 R4/CT2 −0.45 Fno. 2.76 |R5/R6| 0.15 HFOV[deg.] 57.0 f2/f1 0.04 V2/V3 2.38 f/f2 1.59 CT2/CT1 0.31 ΣAT/ΣCT 0.33T12/CT1 0.43 TL/f 5.86 T12/f 1.10 ImgH/f 1.41 (T12 + T23)/CT1 0.47 SD/TD0.26 (R3 − R4)/(R3 + R4) 1.53 Yp32/f 0.17/0.31/0.73 (R4 + R5)/(R4 − R5)−16.44

9th Embodiment

FIG. 9A is a schematic view of an imaging apparatus according to the 9thembodiment of the present disclosure. FIG. 9B shows, in order from leftto right, longitudinal spherical aberration curves, astigmatic fieldcurves and a distortion curve of the imaging apparatus according to the9th embodiment.

In FIG. 9A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor960. The micro imaging system includes, in order from an object side toan image side, a first lens element 910, an aperture stop 900, a secondlens element 920, and a third lens element 930.

The first lens element 910 with negative refractive power has anobject-side surface 911 being planar, an image-side surface 912 beingconcave in a paraxial region thereof, and the image-side surface 912being aspheric. The first lens element 910 is made of plastic material.

The second lens element 920 with positive refractive power has anobject-side surface 921 being convex in a paraxial region thereof, animage-side surface 922 being convex in a paraxial region thereof, andboth the object-side surface 921 and the image-side surface 922 beingaspheric. The second lens element 920 is made of plastic material.

The third lens element 930 with negative refractive power has anobject-side surface 931 being concave in a paraxial region thereof, animage-side surface 932 being convex in a paraxial region thereof, boththe object-side surface 931 and the image-side surface 932 beingaspheric, two inflection points on the object-side surface 931 and oneinflection point on the image-side surface 932. The third lens element930 is made of plastic material.

The micro imaging system further includes an IR cut filter 940 locatedbetween the third lens element 930 and an image surface 950. The IR cutfilter 940 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 960 is disposed onor near the image surface 950 of the micro imaging system.

The detailed optical data of the 9th embodiment are shown in TABLE 17,and the aspheric surface data are shown in TABLE 18, wherein the unitsof the curvature radius, the thickness and the focal length areexpressed in mm, and HFOV is a half of the maximal field of view.

TABLE 17 (9th Embodiment) f = 0.28 mm, Fno = 3.00, HFOV = 61.0 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 5.000 1 Lens 1 Plano 0.400 Plastic 1.534 55.9 −0.50 20.266 ASP 0.400 3 Ape. Stop Plano 0.020 4 Lens 2 0.483 ASP 0.321 Plastic1.544 56.0 0.22 5 −0.121 ASP 0.035 6 Lens 3 −0.175 ASP 0.200 Plastic1.639 23.5 −0.40 7 −0.830 ASP 0.070 8 IR Cut Filter Plano 0.400 Glass1.517 64.2 — 9 Plano 0.039 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 18 Aspheric Coefficients Surface # 2 4 5 6 7 k= −1.0341E+00−1.7418E+00 −6.8505E−01 −3.3433E+00 2.9453E+00 A4= −2.0081E+01−3.1010E+01 2.0285E+02 2.0130E+02 1.0244E+02 A6= 3.4982E+02 4.7587E+03−1.1238E+04 −1.4388E+04 −3.4280E+03 A8= −2.6991E+03 −4.9512E+053.9583E+05 4.9470E+05 6.1242E+04 A10= 8.8056E+03 2.1794E+07 −7.2051E+06−9.0386E+06 −5.6818E+05 A12= −2.9620E+08 5.8506E+07 6.8913E+072.1651E+06

In the 9th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 9th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 17 and TABLE 18and satisfy the conditions stated in table below.

9th Embodiment f [mm] 0.28 R4/CT2 −0.38 Fno. 3.00 |R5/R6| 0.21 HFOV[deg.] 61.0 f2/f1 −0.44 V2/V3 2.38 f/f2 1.26 CT2/CT1 0.80 ΣAT/ΣCT 0.49T12/CT1 1.05 TL/f 6.83 T12/f 1.52 ImgH/f 1.79 (T12 + T23)/CT1 1.14 SD/TD0.42 (R3 − R4)/(R3 + R4) 1.67 Yp32/f 0.11 (R4 + R5)/(R4 − R5) −5.45

10th Embodiment

FIG. 10A is a schematic view of an imaging apparatus according to the10th embodiment of the present disclosure. FIG. 10B shows, in order fromleft to right, longitudinal spherical aberration curves, astigmaticfield curves and a distortion curve of the imaging apparatus accordingto the 10th embodiment.

In FIG. 10A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor1060. The micro imaging system includes, in order from an object side toan image side, a first lens element 1010, an aperture stop 1000, asecond lens element 1020, and a third lens element 1030.

The first lens element 1010 with negative refractive power has anobject-side surface 1011 being planar, an image-side surface 1012 beingconcave in a paraxial region thereof, and the image-side surface 1012being aspheric. The first lens element 1010 is made of plastic material.

The second lens element 1020 with positive refractive power has anobject-side surface 1021 being convex in a paraxial region thereof, animage-side surface 1022 being convex in a paraxial region thereof, andboth the object-side surface 1021 and the image-side surface 1022 beingaspheric. The second lens element 1020 is made of plastic material.

The third lens element 1030 with negative refractive power has anobject-side surface 1031 being concave in a paraxial region thereof, animage-side surface 1032 being convex in a paraxial region thereof, boththe object-side surface 1031 and the image-side surface 1032 beingaspheric, two inflection points on the object-side surface 1031 and twoinflection points on the image-side surface 1032. The third lens element1030 is made of plastic material.

The micro imaging system further includes an IR cut filter 1040 locatedbetween the third lens element 1030 and an image surface 1050. The IRcut filter 1040 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 1060 is disposed onor near the image surface 1050 of the micro imaging system.

The detailed optical data of the 10th embodiment are shown in TABLE 19and the aspheric surface data are shown in TABLE 20 wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 19 (10th Embodiment) f = 0.37 mm, Fno = 3.00, HFOV = 60.4 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano 10.000 1 Lens 1 Plano 0.400 Plastic 1.534 55.9 −0.45 20.240 ASP 0.298 3 Ape. Stop Plano 0.024 4 Lens 2 0.359 ASP 0.356 Plastic1.544 56.0 0.23 5 −0.126 ASP 0.044 6 Lens 3 −0.130 ASP 0.200 Plastic1.660 20.4 −0.40 7 −0.410 ASP 0.100 8 IR Cut Filter Plano 0.400 Glass1.517 64.2 — 9 Plano 0.129 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 20 Aspheric Coefficients Surface # 2 4 5 6 7 k= −2.6536E−01−1.7282E+00 −7.2453E−01 −9.9144E−01 −1.2775E−03 A4= −1.7201E+01−2.4120E+01 1.5270E+02 2.3351E+02 5.3166E+01 A6= 5.0122E+02 4.4562E+03−5.4381E+03 −1.1926E+04 −1.0716E+03 A8= −1.0480E+04 −3.9954E+051.3695E+05 3.8099E+05 1.2667E+04 A10= 8.5861E+04 1.5499E+07 −2.0468E+06−7.3395E+06 −8.2485E+04 A12= −2.2150E+08 1.5176E+07 6.0317E+071.9962E+05 A14= −3.4959E+07 3.6702E+05

In the 10th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 10th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 19 and TABLE 20and satisfy the conditions stated in table below.

10th Embodiment f [mm] 0.37 R4/CT2 −0.36 Fno. 3.00 |R5/R6| 0.32 HFOV[deg.] 60.4 f2/f1 −0.51 V2/V3 2.74 f/f2 1.60 CT2/CT1 0.89 ΣAT/ΣCT 0.38T12/CT1 0.81 TL/f 5.28 T12/f 0.87 ImgH/f 1.34 (T12 + T23)/CT1 0.92 SD/TD0.47 (R3 − R4)/(R3 + R4) 2.09 Yp32/f 0.19/0.51 (R4 + R5)/(R4 − R5)−77.19

11th Embodiment

FIG. 11A is a schematic view of an imaging apparatus according to the11th embodiment of the present disclosure. FIG. 11B shows, in order fromleft to right, longitudinal spherical aberration curves, astigmaticfield curves and a distortion curve of the imaging apparatus accordingto the 11th embodiment.

In FIG. 11A, the imaging apparatus includes a micro imaging system (nototherwise herein labeled) of the present disclosure and an image sensor1160. The micro imaging system includes, in order from an object side toan image side, a first lens element 1110, an aperture stop 1100, asecond lens element 1120, and a third lens element 1130.

The first lens element 1110 with negative refractive power has anobject-side surface 1111 being convex in a paraxial region thereof, animage-side surface 1112 being concave in a paraxial region thereof, boththe object-side surface 1111 and the image-side surface 1112 beingaspheric, and one inflection point on the object-side surface 1111. Thefirst lens element 1110 is made of plastic material.

The second lens element 1120 with positive refractive power has anobject-side surface 1121 being convex in a paraxial region thereof, animage-side surface 1122 being convex in a paraxial region thereof, boththe object-side surface 1121 and the image-side surface 1122 beingaspheric, and one inflection point on the object-side surface 1121. Thesecond lens element 1120 is made of plastic material.

The third lens element 1130 with negative refractive power has anobject-side surface 1131 being concave in a paraxial region thereof, animage-side surface 1132 being convex in a paraxial region thereof, boththe object-side surface 1131 and the image-side surface 1132 beingaspheric, and three inflection points on the image-side surface 1132.The third lens element 1130 is made of plastic material.

The micro imaging system further includes an IR cut filter 1140 locatedbetween the third lens element 1130 and an image surface 1150. The IRcut filter 1140 is made of glass material and will not affect the focallength of the micro imaging system. The image sensor 1160 is disposed onor near the image surface 1150 of the micro imaging system.

The detailed optical data of the 11th embodiment are shown in TABLE 21and the aspheric surface data are shown in TABLE 22 wherein the units ofthe curvature radius, the thickness and the focal length are expressedin mm, and HFOV is a half of the maximal field of view.

TABLE 21 (11th Embodiment) f = 0.64 mm, Fno = 3.38, HFOV = 56.1 deg.Curvature Focal Surface # Radius Thickness Material Index Abbe # Length0 Object Plano Infinity 1 Lens 1 4.546 ASP 0.634 Plastic 1.534 55.9−0.92 2 0.423 ASP 0.804 3 Ape. Stop Plano 0.020 4 Lens 2 0.892 ASP 0.480Plastic 1.534 55.9 0.41 5 −0.238 ASP 0.076 6 Lens 3 −0.256 ASP 0.196Plastic 1.639 23.3 −0.70 7 −0.779 ASP 0.200 8 IR Cut Filter Plano 0.600Glass 1.517 64.2 — 9 Plano 0.387 10 Image Surface Plano — * Referencewavelength is d-line 587.6 nm.

TABLE 22 Aspheric Coefficients Surface # 1 2 4 k= 4.0704E+00 −2.1034E+01−6.0611E+00 A4= 1.0375E+00 1.6735E+01 −1.1878E+00 A6= −1.2738E+00−9.8059E+01 2.9237E+01 A8= 6.0625E−01 3.2992E+02 −2.0488E+03 A10=−1.0896E−01 −4.2776E+02 2.5675E+04 A12= −8.3878E+04 Surface # 5 6 7 k=−6.7300E−01 −1.7466E+00 −6.4938E+01 A4= 2.2165E+01 3.3926E+01 7.5164E+00A6= −3.9970E+02 −8.2688E+02 −1.0510E+02 A8= 5.0186E+03 1.0423E+047.2821E+02 A10= −3.5603E+04 −7.2642E+04 −2.6080E+03 A12= 1.0498E+052.0943E+05 3.8538E+03

In the 11th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in tablebelow are the same as those stated in the 1st embodiment withcorresponding values for the 11th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from TABLE 21 and TABLE 22and satisfy the conditions stated in table below.

11th Embodiment f [mm] 0.64 R4/CT2 −0.49 Fno. 3.38 |R5/R6| 0.33 HFOV[deg.] 56.1 f2/f1 −0.45 V2/V3 2.40 f/f2 1.55 CT2/CT1 0.76 ΣAT/ΣCT 0.69T12/CT1 1.30 TL/f 5.31 T12/f 1.29 ImgH/f 1.55 (T12 + T23)/CT1 1.42 SD/TD0.35 (R3 − R4)/(R3 + R4) 1.73 Yp32/f 0.13/0.41/0.59 (R4 + R5)/(R4 − R5)−27.30

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. It is to be noted thatTABLES 1-22 show different data of the different embodiments; however,the data of the different embodiments are obtained from experiments. Theembodiments were chosen and described in order to best explain theprinciples of the disclosure and its practical applications, and therebyto enable others skilled in the art to best utilize the disclosure andvarious embodiments with various modifications as are suited to theparticular use contemplated. The embodiments depicted above and theappended drawings are exemplary and are not intended to be exhaustive orto limit the scope of the present disclosure to the precise formsdisclosed. Many modifications and variations are possible in view of theabove teachings.

What is claimed is:
 1. A micro imaging system, comprising three lens elements, the three lens elements being, in order from an object side to an image side: a first lens element, a second lens element and a third lens element; each of the three lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the first lens element has negative refractive power, the object-side surface of the first lens element is concave in a paraxial region thereof and has at least one convex surface in an off-axial region thereof; the second lens element has positive refractive power, the object-side surface of the second lens element is convex in a paraxial region thereof, and the image-side surface of the second lens element is convex in a paraxial region thereof, at least one of the object-side and image-side surfaces of the third lens element is aspheric; wherein the micro imaging system has a total of three lens elements, an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the micro imaging system is f, a maximum image height of the micro imaging system is ImgH, and the following conditions are satisfied: 3.80<TL/f<10.0; and 0.95<ImgH/f<3.0.
 2. The micro imaging system of claim 1, wherein the third lens element has both the object-side surface and the image-side surface being aspheric, and the first lens element has the image-side surface being concave in a paraxial region thereof.
 3. The micro imaging system of claim 1, wherein there is at least one inflection point on at least one surface of the third lens element.
 4. The micro imaging system of claim 1, further comprising an aperture stop disposed between the first lens element and the second lens element.
 5. The micro imaging system of claim 1, wherein the focal length of the micro imaging system is f, the maximum image height of the micro imaging system is ImgH, and the following condition is satisfied: 1.9≤ImgH/f<3.0.
 6. The micro imaging system of claim 1, wherein an axial distance between the first lens element and the second lens element is T12, a central thickness of the first lens element is CT1, and the following condition is satisfied: 0.30<T12/CT1<2.50.
 7. The micro imaging system of claim 1, wherein a sum of all axial distances between adjacent lens elements of the micro imaging system is ΣAT, a sum of central thicknesses of the first lens element, the second lens element, and the third lens element is ΣCT, and the following condition is satisfied: 0.20<ΣAT/ΣCT<0.95.
 8. The micro imaging system of claim 1, wherein an axial distance between the first lens element and the second lens element is T12, the focal length of the micro imaging system is f, and the following condition is satisfied: 0.60<T12/f<3.5.
 9. The micro imaging system of claim 1, wherein an absolute value of a curvature radius of the object-side surface of the third lens element is smaller than an absolute value of a curvature radius of the image-side surface of the third lens element.
 10. An imaging apparatus, comprising the micro imaging system of claim 1 and an image sensor disposed on an image surface of the micro imaging system.
 11. An electronic device, comprising the imaging apparatus of claim
 10. 12. A micro imaging system, comprising three lens elements, the three lens elements being, in order from an object side to an image side: a first lens element, a second lens element and a third lens element; each of the three lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the first lens element has negative refractive power, the object-side surface of the first lens element is concave in a paraxial region thereof and has at least one convex surface in an off-axial region thereof; the second lens element has positive refractive power; wherein the micro imaging system has a total of three lens elements, an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the micro imaging system is f, a maximum image height of the micro imaging system is ImgH, a curvature radius of the object-side surface of the third lens element is R5, a curvature radius of the image-side surface of the third lens element is R6, and the following conditions are satisfied: 3.80<TL/f<10.0; 0.95<ImgH/f<3.0; and |R5/R6|<0.70.
 13. The micro imaging system of claim 12, wherein the image-side surface of the first lens element is concave in a paraxial region thereof, the focal length of the micro imaging system is f, a focal length of the second lens element is f2, and the following condition is satisfied: 0<f/f2≤1.09.
 14. The micro imaging system of claim 12, wherein a sum of all axial distances between adjacent lens elements of the micro imaging system is ΣAT, a sum of central thicknesses of the first lens element, the second lens element, and the third lens element is ΣCT, and the following condition is satisfied: 0.20<ΣAT/ΣCT≤0.51.
 15. The micro imaging system of claim 12, wherein a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, the focal length of the micro imaging system is f, the maximum image height of the micro imaging system is ImgH, and the following conditions are satisfied: 0<(R3−R4)/(R3+R4)<3.0; and 1.19≤ImgH/f<3.0.
 16. The micro imaging system of claim 12, wherein an absolute value of a curvature radius of the object-side surface of the second lens element is smaller than an absolute value of a curvature radius of the image-side surface of the third lens element.
 17. A micro imaging system, comprising three lens elements, the three lens elements being, in order from an object side to an image side: a first lens element, a second lens element and a third lens element; each of the three lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the first lens element has negative refractive power, the object-side surface of the first lens element is concave in a paraxial region thereof and has at least one convex surface in an off-axial region thereof; the second lens element has positive refractive power, the image-side surface of the second lens element is convex in a paraxial region thereof; wherein the micro imaging system has a total of three lens elements, an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the micro imaging system is f, a curvature radius of the object-side surface of the third lens element is R5, a curvature radius of the image-side surface of the third lens element is R6, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a central thickness of the first lens element is CT1, and the following conditions are satisfied: 3.80<TL/f<10.0; |R5/R6|<0.70; and 0.10<(T12+T23)/CT1<2.15.
 18. The micro imaging system of claim 17, further comprising an aperture stop disposed between the first lens element and the second lens element.
 19. The micro imaging system of claim 17, wherein the curvature radius of the object-side surface of the third lens element is R5, the curvature radius of the image-side surface of the third lens element is R6, and the following condition is satisfied: |R5/R6|<0.50.
 20. The micro imaging system of claim 17, wherein the axial distance between the first lens element and the second lens element is T12, the axial distance between the second lens element and the third lens element is T23, the central thickness of the first lens element is CT1, and the following condition is satisfied: 0.30<(T12+T23)/CT1<1.50.
 21. The micro imaging system of claim 17, wherein the central thickness of the first lens element is CT1, a central thickness of the second lens element is CT2, and the following condition is satisfied: 0.10<CT2/CT1<1.80.
 22. The micro imaging system of claim 17, wherein an absolute value of a curvature radius of the object-side surface of the first lens element is smaller than an absolute value of a curvature radius of the image-side surface of the first lens element.
 23. A micro imaging system, comprising three lens elements, the three lens elements being, in order from an object side to an image side: a first lens element, a second lens element and a third lens element; each of the three lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the first lens element has negative refractive power, the object-side surface of the first lens element is concave in a paraxial region thereof and has at least one convex surface in an off-axial region thereof; the second lens element has positive refractive power, the image-side surface of the third lens element is concave in a paraxial region thereof; wherein the micro imaging system has a total of three lens elements, an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the micro imaging system is f, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a central thickness of the first lens element is CT1, and the following conditions are satisfied: 3.80<TL/f<10.0; and 0.10<(T12+T23)/CT1<2.15.
 24. The micro imaging system of claim 23, wherein the axial distance between the first lens element and the second lens element is T12, the axial distance between the second lens element and the third lens element is T23, the central thickness of the first lens element is CT1, and the following condition is satisfied: 0.30<(T12+T23)/CT1<1.50.
 25. The micro imaging system of claim 23, wherein a sum of all axial distances between adjacent lens elements of the micro imaging system is ΣAT, a sum of central thicknesses of the first lens element, the second lens element, and the third lens element is ΣCT, and the following condition is satisfied: 0.20<ΣAT/ΣCT≤0.51.
 26. The micro imaging system of claim 23, wherein the axial distance between the first lens element and the second lens element is larger than a central thickness of the third lens element. 